Hydrocarbon conversion process



ay 19, 1942- R. B. DAY ETAL HYDROCARBON CONVERSION PROCESS Filed MaICh 31, 1941 Patented May i9, 1942 ori-ics 2,283,851 nrnaocoN coNvsnsroN rnocsss Roland B. Day and Elmer BQKanhofer, Chicago,

mi., assirs to Universal 01| Products Gompplication ch 31,

4 Claims.

This invention relates to a process for the conversion of relatively high boiling hydrocarbon oil into lighter and more valuable hydrocarbons, and more particularly it is concerned with a process wherein said relatively high boiling hydrocarbon oil is cracked by a combination of thermal and catalytic steps to produce a high K antiknock gasoline.

In the process of our invention the products from a catalytic cracking step are-fractionated to separate gasoline boiling range hydrocarbons, alight reiiux condensate and a heavy'reux condensate. 'I'he heavy reux condensate separated by fractionation of the products from catalytic cracking is coled with a light reux condensate fractionated from the products of a thermal cracking process and the mixture formed into a combined feed for said thermal cracking step. The heavy reiiux condensate separated by fractionation of the products from the thermal cracking step is commingled with the light reux condensate separated from the products of the catalytic cracking step and with the charging stock to form the combined feed for the catalytic cracking step. VThe heavy reux condensate separated from the products of the catalytic cracking step would when returned to said catalytic cracmng step result in -the formation of considerable quantities of carbon on the catalyst and consequently result in an increasein cost of the regenerating of the lcatalyst. In the process of ourinon, this ,fraction containing these coke-forming materials is directed to av thermal cracking step and either cracked or n catalyst with the formation of substantial quantities of gasoline, the products from said catalytic cracking step fractionated to separate'said gasoline, light intermediate conversion products A and heavy intermediate conversion products, commingling said heavy intermediate vconversion 'products with the light intermediate conversion products separated from the products of the thermal cracking step of the process and subjecting said mixture to said thermal cracking step to thermal cracking conditions to form substantial quantities of gasoline, subjecting the products from said thermal cracking stepV to a Chicago, lll., a corporation of Delaware 1941, Serial No. 386,113

products, and heavy intermediate conversion` products, and commingling said heavy intermediate conversion products with the light intermediate conversion products separated from the aforesaid catalytic cracking step and with the raw oil charging stock to form the combinedfeed for the catalytic cracking step for treatment as hereinbefore set forth.

The accompanying diagrammatic drawing illustrates in conventional side elevation one speciiic forrn o'f -apparatus which may vaccomplish the objects of the invention.

Referring to the drawing a relatively high boiling hydrocarbon oil is supplied through line i, valve V2to pump 3 which discharges into line i wherein said charging stock is commingled with a recycle stream formed by coi'nminglingA the heavy intermediate conversion products formed in the thermal cracking step of the system and the light intermediate conversion products formed in the catalytic cracking step of the sys- `tem. This combined feed-is directed from line d to heating coil 5 so disposed as to receive heat from furnace 6. 'I'he oil in passing through heating coil 5 is heated to a temperature within the approximate limits oi 900-1100" F. and at a pressure of theorder of 50-500 pounds per square inch. This heated oil is directed from coil 5 to nline 1 from which, after passing through valve 8, it is supplied to one oiea plurality of reaction chambers having disposed therein a cracking catalyst of the type, such as silica-alumina, composites of silica and alumina with other components, such as hydrated thoria or hydrated zirconia or blends of hydrated silica with hydrated zirconia or hydrated thoria. Although the process is not limited to any number of reactors, for the sake of simplicity, two are shown in the drawing, one of which, in the process beingdescribed,4 is used for the conversion of hydrocarobns, while the catalyst in the other is being subjected to a regeneration process.- The hydrated oil in line- 'l is then directed to line 8 from which it passes through either valve 9 or valve I0, being supplied to reactor A or B as the case may be. The reactors A and B may be of the adiabatic type, that is, the heat absorbed in the conversion process being obtained from the reactants themselves, or if desired, heat exchange types of reactors may be used. Adiabatic reactors have the advantageof simplicity of construction, but in some'caseswhere it is Vdesired to maintain more nearly isothermal conditions,l heat may be supplied by means of combustion gases, Vmolten salts, or the like. In the adiabatic reactors, the catalyst may be disposed in relatively wide beds, while in the heat exchange type, it is often disposed in a plurality' of tubes, or if desired, in beds with heat distributing members. for supplying the heat needed for the reactions. The temperature at the art.

outlet of the reaction chamber is within the range of 8001100 F. with pressures varying from substantially atmospheric to 100 or more pounds per square inch. It is also within the scope of this invention to use, if desired, Acertain diluents, such as steam, in the catalytic cracking zone. The conversion products leave either reactor A or B as the case may be, and are directed into line I I and after passing through valves I2 or I 3' are supplied to line I4 discharging into fractionating column I5. The conversion products are preferably cooled before being supplied to the fractionating column which may be done by quenching them with reflux condensate obtained from said fractionating column. Methods for-ac.

complishing this quenching are well known in the Fractionating column I5 separates as an. overhead product gasoline boiling range hydrocarbons and normally gaseous products, this mixture being removed by way of line I6 controlled by valve I1 from which it is supplied to cooler and condenser I8; The mixture of liquid, to-

gether with undissolved and uncondensed gases, is removed from condenser I8 by way of line. I9 and after passing through valve is directed to receiver and separator 2I. The gases collected in receiver 2| are removed by way of line 22 and after passing through valve 23 are removed from the system. 'I'he oleiinic constituents of said gases may be polymerized yif desired to form gasoline boiling range hydrocarbons, or if de s ired, the isoparanic constituents of said gases may be alkylated with the olens to form a satu rated motor fuelr The liquid collected in receiver 2I. i `s`removed by way of line 24, valve 25 and constitutes a product of the process. It may be stabilized by well known methods to form motor fuel of the desired volatility. condensate is removed as a side cut from fractionating column I5 by way of line 26 and after passingI through valve 21 is supplied to pump 28 which discharges into line 29. This light reflux condensate is commingled in line 30 with the heavy reflux condensate formed in the thermal cracking -step of'thesystem and the mixture directed to `line 4 wherein it is commingled with the charging stock-for the process to form the combined feed for the catalytic cracking step.

The heavy reflux condensate separated from fractionating column I5 is removed by way of line 3l and after-passing through valve 32 is supplied to pump 33 which discharges into line 3.4 controlled by valve 35. After passing` through valve 35 this heavy reflux condensate is commingled with the light reflux condensate 4formed in the thermal cracking step of the`process and the mixturevdirected to heating coil 36 so dis- A lightrefluxy tional vaporization of the hydrocarbons takes place, the mixture of vapors formed in the cracking operation and that due to the flashing operation being removed from said ash chamber by way of line 44 from which. after passing through valve 45 and after quenching, it is supplied to fractionating column 46. The non-vaporous liquid residue separated from the vapors in the ash chamber is removed from the system by way of line 41 contrlled by valve 48.

Gasoline boiling range hydrocarbons and normally gaseous products are separated as an overhead from column 46 by way of line 49 and after passing through valve 50 are supplied to cooler and condenser 5I whereinthe normally liquid products are condensed... The mixture of liquid, together with undissolved and uncondensed gases, is directed from cooler and condenser 5I to line 52 controlled by valve 53 from which it is supplied to receiver and separator 54. 'I'hegases separated in receiver-54 are removed from the system by way of line 55 controlled by valve 56. The oleflnic constituents of said gases may be polymerized to form a motor. fuel, or if desired. the isoparaffinic constituents thereof may be a1- kylated by the oleflns to form a `saturated motor fuel. 'I'he liquid collected in receiver 54 is removed by way of line 51 controlled by valve 58 and constitutes a product of the process and may be stabilized to form a motor fuel of the desired volatility. `I

'I'he light reflux condensate is removed as a side cut from column 46 by way of line 59'and after passing through valve is supplied to pump 6I., discharging through line 62, valve 63 into line 34 wherein said light reflux condensate is commingled with the heavy reflux condensate formed inthe catalytic cracking step and the mixture is subjected to thermal cracking as hereinbefore set forth. The heavy reflux condensate, freed from carbon-forming materials by the `flashing operation conducted in chamber 43 as hereinbefore set forth, is removed from col- 'umn 46 by way of line 64 and after passing through valve is supplied to pump 66 which discharges into line 30 wherein said heavy reflux condensate is commingled with the light reflux condensate formed in the catalytic cracking step and the mixture directed to line 4 wherein it is commingled with thecharging stock and the mixture subjected to catalytic cracking as hereinbefore set forth. A An example of one specicloperation of the process as it may be accomplished in an apparaposed asto receive heat from furnace 31. The I and heavy intermediate conversion products products from heating coil 36 are at a temperature within the approximate limits of 875-1000 lj'. and a pressure which may vary from about.50 toabout 400 pounds per square inch and are directedV t0 liner 38 from. which, after passing through valve 39, they are supplied to reaction chamber 40. The function of this insulated re# action chamber is, a continuance of the cracking reaction begun in coil 36. The reaction products from chamber 40 are4 directed to line 4I and 25-200 pounds per square inch. Owing tothe reduction of'pressure-in flash chamber 43 additus such as illustrated and above described is approximately as follows: Charging oil comprising a 34.5 A. P. I. gravity Pennsylvania gas oil is commingled with light intermediate conversion products from the catalytic cracking step from the thermal cracking step, vaporized and heated to a temperature of about 960 F. These heated vapors pass in contact with a mass of ing and insumciently converted hydrocarbons.

The gasoline is separated from the normally gaseous products and collected as a product of the process.

The insufficiently converted hydrocarbons from the thermal cracking step are fractionated into light insuiliciently converted hydrocarbons and heavy nsufdciently converted hydrocarbons. 'Ihe light insuillciently converted hydrocarbons from the thermal cracking step are commingled with the heavy insuillciently converted products from the catalytic cracking step and the mixture subjected to thermal cracking at a temperature of 920 F. and a pressure of 300 pounds per square inch at the outlet of the heating coil, employing a reaction chamber and utilizing such a time of reaction that approximately 20% of the charge of the thermal cracking step is cracked per pass. The thermally cracked products are then subjected to a flashing operation to separate nonvolatile liquid residue from the vaporous reaction products. The products from the thermal cra/cking step are then fractionated to separate gasoline, normally gaseous products, light intermediate conversion products and heavy intermediate conversin products. The heavy intermediate conversion products from the thermal cracking step are then blended with the light intermediate conversion products from the catalytic cracking step and with a gas oil charging stock to form the combined feed for the catalytic cracking step for treatment as hereinbefore set forth.

For an operation employing conditions as above mentioned, one may obtain approximately 45.2% of 400 end point catalytically 'cracked gasoline having an octane number of '19.5, approximately 22.8% of 400 end point thermally cracked gasoline of 69.5 octane number and 20.0% liquid residue of 8.5 A. P. I. gravity, the balance being principally carbon and gaseous products.

We claim as our invention:

1. A process for the production of gasoline which comprises subjecting a combined feed formed as hereinafter set forth to catalytic cracking, fractionating from the products of said catalytic cracking step gasoline, light intermediate conversion products, and heavy intermediate conversion products, commingling said heavy intermediate conversion products withI light intermediate conversion products formed -hydrocarbon oil charging stock to form the combined feed for the catalytic cracking step.

2. A process for the production ofa gasoline which comprises subjecting a combined feed `*formed as hereinafter set forth to the action of arsiliceous cracking catalyst at a temperature within the approximate limits of 8001l00 F'. and a pressure of from substantially atmospheric to approximately 100 pounds per square inch and for a time-ofcontact adequate to the formation of substantial quantities of gasoline, fractionating from" the products of said catalytic cracking step gasoline, light intermediate conversion products and heavy intermediate conversion products, commingling said heavy intermediate conversion products with light intermediate conversion products formed in a thermal cracking step l.as hereinafter set forth and subjecting the mixture to a temperature within the approximate limits of 8751000 F. and at a pressure of from about to about 400 pounds per square i inch and for a suilicient period of time to form .substantial quantities of gasoline, separating the products of said thermal cracking step into a non-vaporous liquid residue and a vaporous fraction, fractionating said vaporous fraction to separate gasoline and normally gaseous products, light intermediate conversion products and heavy intermediate conversion products, and commingling the heavy intermediate conversion products from the thermal cracking with the light intermediate conversion products from the catalytic cracking step and with a relatively high boiling hydrocarbon oil charging stock to form the combined feed for the catalytic cracking step.

3. A process for the production of gasolineby a combination of a thermal cracking step and a catalytic cracking step which comprises sub jecting a combined feed` formed as hereinafter set forth to catalytic cracking, fractionating the products of said catalytic cracking step in commingled state with a raw oil charging stock to separate gasoline and normally gaseous products,

step into a non-vaporous .liquid residue and a vaporous fraction, fractionating said vaporous fraction to separate gasoline and normally gaseous products, a light reflux condensate and a heavy reflux condensate, and commingling the heavy reflux condensate from the thermal cracking step with the light redux condensate from the aforesaid catalytic cracking step to form the combined feed for the aforesaid catalytic cracking step. v

4. A process for the production of gasoline n which comprises maintaining a catalytic crack ing step and a thermal cracking step. subjecting conversion products from the thermal cracking step to a vaporizing and separating step to separate a non-volatile liquid residue from the remaining vapors, fractionating said remaining vapors to separate gasoline, normally gaseous products, light intermediate conversion products and heavy intermediate conversion products,

fractionating the products from the catalytic cracking step to separate gasoline, normally gasi eous products, light intermediate conversion products, and heavy intermediate conversion products, commingling the light intermediatev conversion products from the thermal cracking" step with the heavy intermediate conversion products from the catalytic cracking step to form 1 the combined feed for the thermal cracking step and commingling the heavy intermediate conversion products from the thermal cracking step with the light intermediate conversion products from the catalytic cracking step and a charging stock comprising fractions boiling above the range of gasoline and subjecting this mixture to the aforesaid catalytic cracking step.

- ROLAND B. DAY.

ELMER. R. KANHOFER. 

